Albert Alier

Multiplex PCR of sonication fluid accurately differentiates between prosthetic joint infection and aseptic failure

OBJECTIVE Cultures have limited sensitivity in the diagnosis of prosthetic joint infection (PJI), especially in low-grade infections. We assessed the value of multiplex PCR in differentiating PJI from aseptic failure (AF). METHODS Included were patients in whom the joint prosthesis was removed and submitted for sonication. The resulting sonication fluid was cultured and investigated by multiplex PCR, and compared with periprosthetic tissue culture. RESULTS Among 86 explanted prostheses (56 knee, 25 hip, 3 elbow and 2 shoulder prostheses), AF was diagnosed in 62 cases (72%) and PJI in 24 cases (28%). PJI was more common detected by multiplex PCR (n=23, 96%) than by periprosthetic tissue (n=17, 71%, p=0.031) or sonication fluid culture (n=16, 67%, p=0.016). Among 12 patients with PJI who previously received antibiotics, periprosthetic tissue cultures were positive in 8 cases (67%), sonication fluid cultures in 6 cases (50%) and multiplex PCR in 11 cases (92%). In AF cases, periprosthetic tissue grew organisms in 11% and sonication fluid in 10%, whereas multiplex PCR detected no organisms. CONCLUSIONS Multiplex PCR of sonication fluid demonstrated high sensitivity (96%) and specificity (100%) for diagnosing PJI, providing good discriminative power towards AF, especially in patients previously receiving antibiotics.

Advantages of sonication fluid culture for the diagnosis of prosthetic joint infection

OBJECTIVES The sensitivity of periprosthetic tissue culture is inadequate for the diagnosis of prosthetic joint infection (PJI). We investigated and compared the values of sonication fluid culture and periprosthetic tissue culture for diagnosing PJI. METHODS Included were patients whose joint prosthesis had been removed for any reason. The resulting sonication fluid and periprosthetic tissues were cultured for 14 days. RESULTS Of 231 explanted prostheses, aseptic failure was diagnosed in 162 cases (70%) and PJI in 69 (30%). In PJI cases, sonication fluid culture detected 62 microorganisms and periprosthetic tissue culture detected 45. Tissue and sonication fluid cultures showed sensitivities of 61% and 81%, respectively (p < 0.01), with specificity of 100% and 99%, respectively. On day 1, tissue and sonication fluid cultures were positive in 13% and 28% (p = 0.013) of PJI cases respectively, and on day 2, in 26% and 48% (p = 0.002) of cases. Four anaerobes grew in sonication fluid culture after 7-13 days incubation, whereas tissue culture missed 3 of these. Prolonged incubation of sonication fluid did not detect any organisms in the cases of aseptic failure. CONCLUSIONS Sonication fluid culture provides a more rapid diagnosis and detects about 30% more pathogens, although anaerobic organisms require up to 2 weeks of incubation.

Prosthesis Failure Within 2 Years of Implantation Is Highly Predictive of Infection

BackgroundThe outcome of revision surgery depends on accurate determination of the cause of prosthesis failure because treatment differs profoundly among aseptic loosening, mechanical failure, and prosthetic joint infections (PJI).Questions/purposesWe sought to determine (1) the predictive role of the interval from primary to revision surgery in determining the reason for prosthesis failure of a hip, knee, shoulder, or elbow arthroplasty, and (2) whether positive cultures during revision surgery for aseptic loosening were associated with shorter event-free survival of the prosthesis.MethodsAll patients undergoing revision surgery between July 2010 and January 2012 were included in a prospective cohort of 112 patients, and were classified as having had failure from aseptic loosening (56%), mechanical failure (15%), or PJI (29%). To make the diagnosis of PJI, at surgery we used a standardized enhanced diagnostic approach in all patients including sampling of five periprosthetic tissue specimens, sonication of removed prosthetic components, prolonged incubation of aerobic and anaerobic cultures, and multiplex PCR of sonication fluid in aseptic loosening cases. Kaplan-Meier survival and Cox proportional hazards regression analysis were performed.ResultsThe median time from primary to revision surgery was (p < 0.001) longer for patients with aseptic loosening (7.8 years) than for patients with mechanical failure (1.6 years) or PJI (2 years). No difference in the time to revision was observed for patients with aseptic loosening with positive or negative microbiological cultures (p = 0.594). Propionibacterium acnes was cultured below the established microbiological criteria for positivity in 12 (19%) procedures that had been presumed to have been revisions for aseptic loosening.ConclusionsPJI should be considered in all revisions performed within 2 years of implantation even in the absence of clinical or laboratory findings suggestive for infection. However, the growth of low-virulence microorganisms below the cut-off in revisions for apparent aseptic loosening is not associated with early prosthesis failure.Level of EvidenceLevel II, diagnostic study. See the Instructions for Authors for a complete description of levels of evidence.

Improved Diagnosis of Orthopedic Implant-Associated Infection by Inoculation of Sonication Fluid into Blood Culture Bottles

ABSTRACT Sonication improved the diagnosis of orthopedic implant-associated infections (OIAI). We investigated the diagnostic performance of sonication fluid inoculated into blood culture bottles in comparison with that of intraoperative tissue and sonication fluid cultures. Consecutive patients with removed orthopedic hardware were prospectively included and classified as having OIAI or aseptic failure (AF) according to standardized criteria. The diagnostic procedure included the collection of five intraoperative tissue cultures and sonication of the removed device, followed by conventional culture of the sonication fluid. Cultures were incubated for 7 days (aerobic) or 14 days (anaerobic). In addition, 10 ml of sonication fluid was inoculated into each aerobic and anaerobic BacT/Alert FAN blood culture bottle and incubated in the automated blood culture system for 5 days. Of 75 included patients, 39 had OIAI and 36 AF. The sensitivity of sonication fluid inoculated into blood culture bottles (100%) was higher than that of conventional sonication fluid (87%; P = 0.05) or intraoperative tissue cultures (59%; P < 0.01). Previous antibiotic therapy reduced the culture sensitivity of conventional sonication fluid to 77% and that of intraoperative tissue to 55%, while it remained 100% for blood culture-inoculated sonication fluid. The time to positivity was shorter in blood culture-inoculated sonication fluid, with detection of 72% of microorganisms after 1 day of incubation, than for intraoperative tissue and conventional sonication fluid cultures, with detection of 18% and 28% of microorganisms, respectively. In conclusion, compared to conventional sonication fluid and intraoperative tissue cultures, sonication fluid inoculated into blood culture bottles improved the diagnosis of OIAI and considerably reduced the time to culture positivity.

Time trends in the aetiology of prosthetic joint infections: a multicentre cohort study

It is important to know the spectrum of the microbial aetiology of prosthetic joint infections (PJIs) to guide empiric treatment and establish antimicrobial prophylaxis in joint replacements. There are no available data based on large contemporary patient cohorts. We sought to characterize the causative pathogens of PJIs and to evaluate trends in the microbial aetiology. We hypothesized that the frequency of antimicrobial-resistant organisms in PJIs has increased in the recent years. We performed a cohort study in 19 hospitals in Spain, from 2003 to 2012. For each 2-year period (2003-2004 to 2011-2012), the incidence of microorganisms causing PJIs and multidrug-resistant bacteria was assessed. Temporal trends over the study period were evaluated. We included 2524 consecutive adult patients with a diagnosis of PJI. A microbiological diagnosis was obtained for 2288 cases (90.6%). Staphylococci were the most common cause of infection (1492, 65.2%). However, a statistically significant rising linear trend was observed for the proportion of infections caused by Gram-negative bacilli, mainly due to the increase in the last 2-year period (25% in 2003-2004, 33.3% in 2011-2012; p 0.024 for trend). No particular species contributed disproportionally to this overall increase. The percentage of multidrug-resistant bacteria PJIs increased from 9.3% in 2003-2004 to 15.8% in 2011-2012 (p 0.008), mainly because of the significant rise in multidrug-resistant Gram-negative bacilli (from 5.3% in 2003-2004 to 8.2% in 2011-2012; p 0.032). The observed trends have important implications for the management of PJIs and prophylaxis in joint replacements.

Preoperative antibiotic prophylaxis in prosthetic joint infections: not a concern for intraoperative cultures

BACKGROUND Culture negative prosthetic joint infections (PJI) still remain an issue even with the advantages of the new diagnostic tools for PJI. This is why some orthopedic surgeons have reservations relative to the use of preoperative antibiotic prophylaxis when a PJI is suspected. The purpose of the present study was to evaluate the influence of preoperative antibiotic prophylaxis on intraoperative cultures. MATERIAL AND METHODS An enhanced diagnostic protocol for PJI (Zimmerli criteria) was used for the inclusion criteria in order to collect all PJI that were seen in a university hospital. Patients were prospectively randomized into two groups. The control group received the classical preoperative antibiotic prophylaxis. The study group did not receive prophylaxis prior to surgery. RESULTS There were 14 patients in each group. They correspond to 13 total hip arthroplasty infections, 12 total knee arthroplasty infections and 3 reverse shoulder prosthesis infections. There were 10 patients in the study group and 10 patients in the control group with at least one positive microbiological criterion (P > 0.05). There were 4 patients in each group with a culture negative PJI (P > 0.05). CONCLUSIONS Preoperative antibiotic prophylaxis does not affect intraoperative cultures in suspected or confirmed PJI. Therefore it is essential to deliver antibiotic prophylaxis in any patient in which a prosthesis is to be implanted in order to protect the prosthesis from infection.

Cervicocephalic medial screw migration after intertrochanteric fracture fixation, OTA/AO 31-A2, using intramedullary nail Gamma3: report of 2 cases and literature review.

Summary: Cervicocephalic screw medialization is a rare complication after intertrochanteric fracture synthesis with a Gamma3-type intramedullary nail. Only 6 cases of intrapelvic penetration by Gamma3 lag screw have been described. We now describe 2 additional cases and a review of the literature.

Distal humeral epiphysiolysis in the newborn: utility of sonography and differential diagnosis ☆

Fracture-separation of the distal humeral epiphysis in newborn is a rare entity, usually the result of a traumatic delivery. It can mimic elbow dislocation and, due to the absence of ossification of the epiphysis at that time, cannot be diagnosed radiographically. However, ultrasound is an important diagnostic tool for this purpose because it is able to clearly visualize the cartilaginous epiphysis. In addition, it allows the differential diagnosis with posterior elbow dislocation whose therapeutic management and prognosis are different. We report the case of a preterm newborn in which a fracture-separation of the distal humeral epiphysis was diagnosed with the help of sonography. The purpose of this report is to emphasize the utility of echography as a cheap, available, and noninvasive tool for the evaluation of the nonossified epiphysis in the newborn elbow.

Results of cement spacer sonication in the second stage of two-stage treatment of shoulder arthroplasty infection

BackgroundThe objective of this study is to present the results of cement spacer sonication in the second stage of two-stage treatment of shoulder arthroplasty infection and to determine the rate of positive cultures in the second-stage surgery in shoulder arthroplasty and its meaning.MethodsTwenty-one patients (22 cement spacers) treated with two-stage surgery because of a shoulder arthroplasty infection were included. In the second stage, the cement spacer was sent for sonication and at least four tissue cultures were obtained. Epidemiological data, comorbidities, sensitivity of the microorganisms to the antibiotic loaded in the cement spacer in the first revision surgery, time elapsed since an antibiotic was last administered until second revision procedure, functional shoulder status at last follow-up, and any complication were recorded.ResultsThree out of the 22 cases (13.6%) presented positive cultures at the second-stage surgery. Periprosthetic tissue culturing detected the three positive culture cases in the second stage while the cement spacer sonication detected two and missed one. Considering periprosthetic tissue culturing as the standard procedure, the cement spacer sonication showed sensitivity at 66.6%. Recurrent infection over time was considered present in 3 patients; two of them had been previously diagnosed with a positive culture at the second stage (66.6%).ConclusionsA good number of patients (13.6%) present a positive culture at the second stage of the two-stage surgical procedure for infected shoulder arthroplasty, and those patients seem to be at high risk for recurrent infection. Periprosthetic tissue cultures have a higher sensitivity to detecting a positive culture at the second stage than cement spacer sonication.